This invention relates to a sulfoxidation process and more particularly to a process for converting paraffins to biodegradable alkali metal salts of sulfonic acids.
The present invention constitutes an improvement over the process disclosed and claimed in commonly assigned U.S. Pat. No. 3,743,673 issued July 3, 1973, the disclosure of which is incorporated by reference in the instant application.
The process disclosed in the above-mentioned patent has been found at times to yield products which are not color and pH stable owing mainly to ferric contamination due to plant conditions such as the use of certain iron alloys. In U.S. Pat. No. 3,743,673 no disclosure was made of an immediate separation of the heavy product phase from the unreacted paraffin charge. It has now been found that allowing the heavy product phase to remain at the reaction temperature and in the presence of sulfur dioxide as described in the patent causes irreversible changes in the product; the resulting final product's color and color stability cannot be then improved by normal working-up procedures.
U.S. Pat. No. 3,743,673 also teaches that free gases should be vented from the settler tank. This procedure causes the heavy product phase to remain in the presence of dissolved sulfur dioxide which causes adverse effects on the color of the product.
U.S. Pat. No. 3,743,673 also did not teach the hydrolysis of the separated and degassed heavy product phase over an optimum period of time and at the boiling point of the phase to completely hydrolyse the acid precursors present therein. Such hydrolysis now has been found essential for the obtaining of color stable products.